Lirghousb electbjc



Jan. 10, 1928.

R. T. PIERCE ELECTRICAL MEASURING ms'muumur Filed Jan. 30. 1923 as an 9 23l9l'79 2| INVENTOR aym and T. Pierce a) WITNESSES:

BY W I W/TORNEY lit l it

Hill

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all; Itti Application filed .ji'airaary ll ly invention. relates to electr cal measuring instruments and particua :y to meats; for limiting the movement oi" the hides or pointer members thereof.

Une object or my inve tion is to provide means oil the above indicated character that shall. so absorb the shock attending; the sudden stoppinrr of an. instrument pointer as to prevent injury to the latter.

.[lnother object of my invent is to provide means that shall. co-operate with an element other than the pointer for limiting; the movement of an instrument pointer.

ill. turther object oft my invention to so protect an instrument pointer against sudden stops as to render the instrument more durable and etlective.

lleretofore, it has been usual, in electrical. measuring; instruments, to provide a stop member for engagement with the pointers Which, by reason of inertia and re .tivelv long delicate construction, were i piently in ured by such engagement. This was caused by the concentration of the forces,

" between the stop member and the pointer,

at a local point on the pointer.

in practicing my invention, l: provide a yieldable stop member for limiting move ment oi? the pointer that so engages an ole-- menh other than the pointer, to more Widely distribute the interacting]; collision -forces, resulting when. the pointer is stopped, to reduce the likelihood ot injury to the pointer and of atliecting" the accuracy Oil the instrument.

lh ip ure 1 ol the accompanying; drawing; is a front view of a portion oil an electrical measuring instrument embodying my invention, and

llig. is an end view of the device shown in 'l.

'l he device conun'ises, in general, a per rnanent magnet l, pole members 2 theretor, a core member 3 disposed between the members 2, side plates or brackets t for holding the core member 3 in position, a bobbin 5 up on which a coil 6 wound, a pointer 7 carried by the bobbin 5, a bridge structure for supporting the bobbin hand stop inemhers 9 tor limiting the movement ol the pointer 7.

The permanent magnet 1, only a portion of which is shown, is preferably oi: the usual horseshoe type, to the ends il of which. th

pole members are secured. llhe latter are provided. with arcuate inner surfaces lit be tween which. the cylindrical core member so supported. by the plates l, as to provide a relatively narrow arcuate air gap 14.

The bobbin. 5 is preferably oi: rectangular irame shape having lon itirplinal side per-- tions movable in the air ap 14 and end portions 15 which suport shaft portions 16 and it? mounted, respectively, at the upper and lower ends ot the bobbin. The shaft men1- her 16, upon Which the pointer 7 is mounted, is provided With a suitable hearing (not shown.) and the lower shaft member 17 is mounted in hearin member 19 that is sup ported by the brid, ,'np; member lhe latter supported, at its ends, by standards 201 that are secured to the pole pieces by screws 911.

Each stop member 9 comprises an eyelet or supporting portion flit for mounting around one elf the screws Ell, a portion E23 projecting radially therefrom and extending transverse ly to the longitudinal axis oi the bobbin 5 and a yieloablo stop portion 24: projecting into the air gap l liior engagement with the bobbin. 5.

blince the portions 24; constitute relatively long; lever arms, relative to the portions 23 Oil the members 9, they Will yield when engagged by the bobbin 5 at the limits of its movement to thus absorb the shock attending the sudden stopping of the moving system.

By the above described arrangement of parts, the pointer is tree from engagement With any stationary element and is therefore prevented :trom injury from this cause. lieinr tree from violent shocks, the pointer and moving; system are less likely to be disturbed in the initial setting thereof and the iustrument as a Whole is rendered more durable and etlective.

l l hile l have shown and described a particular form 0t my invention, changes may be eiilected therein Without departing tron] the spirit and scope thereof, as set Forth in the appended claims.

I claim as my invention:

1. lln an electrical measuring instrument. the combination with a stationary structure having an air and a pivoted. element movable in said air gap, oil a stop member lutvi'r gg a portion secured to a side at the stationary structure and a resilient portion for engagement with the movable element laterally projecting from said first portion into the air gap for positioning by the stationary structure.

2. In an electrical measuring instrument, the combination with a stationary structure having an air gap and a pivoted element movable in said air gap, of a pair of stop members for the movable element secured to the stationary structure, each of said stop members having a portion secured to a side of the stationary structure, a portion projecting from said portion to a position opposite one end of said air gap and a resilient portion projecting from the latter portion into the air gap for positioning by the stationary structure.

3. In an electrical measuring instrument,

the combination with a stationagy strlirturo having an air gap and a pivoied element movable in said air gap, of a pair of stop members, each constructed of resilient sheet material having an enlarged apertured portion secured to a side of the stationary element, an elongated strap portion proiecting from said enlarged portion to a position opposite one end of said air gap, and a strap portion projecting from the latter portion into the air gap for positioning by the stationary structure and having a stop surface at right angles to a surface on the movable element.

In testimony \vhcreo'f, l have hereunto subscribed my name this 11th day of January, 1923.

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